The long term objectives of this project are to better understand the mechanisms by which autoimmune uveitis occurs in a novel spontaneous animal model of the disease. Our new model involves mice that are deficient for the Autoimmune Regulator (Aire) gene, which was identified by positional cloning efforts on patients with a polyglandular autoimmune syndrome called APECED (Autoimmune PolyEndocrinopathy Candidiasis Ectodermal Dystrophy). Both Aire-deficient mice and humans develop an autoimmune attack directed against the eye and the mice provide the first spontaneously occurring model of autoimmune eye disease. In addition, previous work by our group and others has shown that Aire helps regulate the ectopic expression of many self-antigens in the thymus gland and studies here will help to further clarify the link between the thymus and the generation of autoimmune disease in the eye. The general strategy is to utilize aire-deficient mice as a tool to unravel how uveitis occurs in these animals. Aire-deficient mice generate an autoimmune attack directed against the eye that is characterized by both a mononuclear infiltrate in the retina and by serum autoantibodies directed against the photoreceptor layer of the retina. The autoantibodies and eye-reactive lymphocytes present in aire-deficient mice can be utilized to identify those antigens in the eye that are being targeted by the autoimmune response. The specific aims are to tightly define the key aspects of the autoimmune response against the eye in aire-deficient mice. Three major goals are envisioned: (1) define and purify the retinal antigens targeted by autoantibodies and T cells in aire-deficient mice; (2) determine the key effector populations of lymphocytes responsible for aire-deficient uveitis; (3) determine the regulation of the thymic expression of retinal autoantigens by aire and their impact on thymocyte selection. Previous work involving animal models of autoimmune uveitis has relied on the induction of disease by immunization with inciting antigens. Because our animal model occurs spontaneously, it affords the opportunity to potentially identify new autoantigens associated with uveitis and also those that are more tightly linked to disease. Aire appears to regulate the expression of many self-antigens in the thymus and studies here will help expand our knowledge of which eye antigens are regulated in the thymus and how tolerance to these antigens may be broken in its absence. These studies have important implications for understanding how autoimmunity in the eye occurs and have a direct link to the clinical realm, as patients with a defective Aire gene also develop uveitis.